Quick opening device for dry-pipe valves of automatic sprinkler systems

ABSTRACT

A component for automatic sprinkler systems employed for fire protection is provided which is useful in dry-pipe systems to cause rapid opening of the dry-pipe valve of such systems in response to a slight but rapid decrease of air pressure in the sprinkler piping network attendant upon opening of a sprinkler head. Slow decreases in such pressure in relation to atmospheric pressure are offset by an atmospheric bleed valve, a readily accessible adjustment for altering and visibly indicating the trip-off pressure is provided, and provision is made for either electrical or pneumatic operation.

United States Patent Charles F. Willms Rutherford, NJ. 863,985

Oct. 6, 1969 Nov. 2, 1971 Norris Industries, Inc. Los Angeles, Calif.

Inventor Appl. No. Filed Patented Assignee QUICK OPENING DEVICE FORDRY-PIPE VALVES OF AUTOMATIC SPRINKLER SYSTEMS 4 Claims, 5 Drawing Figs.

U.S. Cl 169/17, 169/19 Int. Cl A62c 35/00 Field of Search 169/ 19-22, 17

References Cited UNITED STATES PATENTS 712,682 11/1902 Jefferson 169/201,050,036 l/l9l3 Mueller et al 169/19 1,491,301 4/1924 Grafflin 169/201,900,300 3/1933 Paden et al. 169/19 X 2,591,959 4/1952 McRae 169/20Primary Examiner-Lloyd L. King Attorney-Huebner & Worrel ABSTRACT: Acomponent for automatic sprinkler systems employed for fire protectionis provided which is useful in drypipe systems to cause rapid opening ofthe dry-pipe valve of such systems in response to a slight but rapiddecrease of air pressure in the sprinkler piping network attendant uponopening of a sprinkler head. Slow decreases in such pressure in relationto atmospheric pressure are offset by an atmospheric bleed valve, areadily accessible adjustment for altering and visibly indicating thetrip-off pressure is provided, and provision is made for eitherelectrical or pneumatic operation.

AIR SIDE OF SYSTEM i were: SUPFLY PATENTEnuuv 2 I971 3,616,860

sum 10F 2 TO WATER MO OR AIR SIDE OF SPRINKLER SYSTEM H 2 .On/E/vro/q i64024.55 1 W/ZLMS QUICK OPENING DEVICE FOR DRY-PIPE VALVES OF AUTOMATICSPRINKLER SYSTEMS BACKGROUND OF THE INVENTION 1. B. Field of theInvention Automatic sprinkler systems embody a network of overheadpiping extending throughout a building or area and provided at spacedintervals with sprinkler heads, which are essentially heat-responsivevalves which open under the influence of a local conflagration todischarge water from the piping over the area covered by the openedsprinkler or sprinklers.

In locations in which there is no exposure of the piping of such systemsto freezing temperatures, a wet-pipe system may be installed. In such asystem, water is held in the piping throughout the system, andimmediately discharged whenever a sprinkler head opens.

However, in locations in which the piping is likely to be exposed tofreezing temperatures, a dry-pipe system must be installed. In such asystem, air is held in the piping throughout the network of piping. Amain control valve, known as a drypipe valve, which is located in anarea not exposed to freezing temperatures, opens in response to a dropin air pressure in the piping network occasioned by the opening of asprinkler head, allowing water to flow into the piping network anddischarge through the open sprinkler head or heads.

The interval between the opening of a sprinkler head of such a dry-pipesystem and the discharge of water from it necessarily lengthens as thesize of the system increases, because the rate at which air can bedischarged through an open sprinkler head is limited and therelationship of the volume of air so discharged to the total volume ofair in the piping network becomes smaller as that total volumeincreases.

Among the standards agreed upon for automatic sprinkler systems is onefixing a limit on the interval between the opening of a sprinkler headand the discharge of water from it; it being required to be short enoughto afford a reasonable assurance that a fire will not intensify orspread beyond control. In order to comply with this interval standard,it has been necessary in large dry-pipe systems, to provide devices forcausing the dry-pipe valve to open in response to the opening of asprinkler head, at an earlier point in time than it would in the absencethereof. Such devices are known as quick-opening devices, exhausters, oraccelerators, and it is to the improvement of this class of devices thatthe present invention is directed.

2. Description of the Prior Art Disclosures of various types of dry-pipevalves and quickopening devices are compiled in Chapter IX of the FireProtection Handbook," 12th Edition, compiled by the National FireProtection Association and published by The Riverside Press, Cambridge,Massachusetts, 1962.

A principal type of dry-pipe valve, as disclosed in the U.S. Pat. No.2,667,934 of Rowley dated Feb. 2nd, 1954, comprises an intermediatechamber disposed between an inlet chamber connected to the water mainand an outlet chamber connected to the sprinkler piping network; anormally closed valve being disposed between the inlet and outletchambers. This valve is prevented from opening as long as the pressureof the air in the sprinkler piping network, which is in excess of theatmospheric pressure, exceeds a predetermined magnitude. Even in theabsence of any quickopening device, the water supply pressure will causethe valve to open if the pressure of the air in the sprinkler pipingnetwork falls below a critical point.

Various types of devices have been provided for expediting the openingof such dry-pipe valves upon a decrease in the air pressure in thesprinkler piping network to a predetermined point higher than the pointat which such opening would occur were such a device not provided. Onetype of such device responds to a decrease in pressure in the sprinklerpiping network to exhaust air therefrom into the intermediate chamber ofthe dry-pipe valve, thus rapidly equalizing the pressure above and belowa diaphragm forming a part of the valve between the inlet and outletchambers and permitting the water pressure to open the valve.

Such devices must, however, be capable of discriminating between rapidpressure drops in the sprinkler piping network resulting from opening ofa sprinkler head and requiring prompt opening of the dry-pipe valve, andslow pressure drops resulting from lowering of air temperature in thepiping network, etc., which must not be allowed to cause opening of thedry-pipe valve. For this reason, prior devices of this type haveincluded dual internal chambers communicating through a restrictedorifice; one such chamber being connected to the sprinkler pipingnetwork, and the arrangement being such that the device operates onlywhen the pressure in the latter chamber falls below the pressure in theother chamber by a predetermined amount due to inability of therestricted orifice to effect sufficiently rapid equalization.

The restricted orifices of such devices are subject to clogging,allowing them to cause opening of the dry-pipe valve in response to evenslow drops in the pressure of the air in the sprinkler piping networkwhich, of course, is highly undesirable. Furthermore, the point at whichsuch devices will cause opening of the dry-pipe valve can be changedonly by adjustment of the restricted orifice.

SUMMARY OF THE INVENTION In contrast to the prior devices referred toabove, which rely upon sensing of differences between the ambientpressure in a secondary chamber communicating unrestrictedly with thepiping network and the pressure retained in a primary chambercommunicating with the piping network through a restricted orifice tocause opening of the dry-pipe valve, the device of the present inventionsenses differences between the ambient pressure in a secondary chambercommunicating unrestrictedly with the piping network and the pressure ina primary chamber communicating through a restricted orifice with theatmosphere instead of with the secondary chamber; the restricted orificebeing provided so that slow decreases in pressure in the piping networkmay be offset by the flow of air through the restricted orifice, whilerapid decreases in pressure in the piping system will produce a. partialvacuum in the primary chamber the volume of which; varies inversely withrespect to that of the secondary chamber.

This makes it possible to dispose the restricted orifice between theinterior and exterior of the device instead of between two chamberswithin the device, thus reducing the likelihood of clogging of theorifice and rendering it more easily accessible for cleaning orreplacement in the event such clogging should occur.

The primary chamber may be connected directly to a conventional vacuumresponsive electrical switch adapted for connection to a solenoid valveso that, upon the occurrence of a partial vacuum in the primary chamber,the solenoid valve will open and admit fluid under pressure to the splitseat of the dry-pipe valve of a dry-pipe sprinkler system, thus causingthe dry-pipe valve to open and admit water under pressure to thesprinkler pipe network much sooner than it would open in response to anair pressure drop in that network.

Alternatively, the primary chamber may be connected to a pilot valveoperating mechanism so that, upon the occurrence of a partial vacuum inthe primary chamber, a valve will be opened to admit fluid underpressure to the split seat of such a dry-pipe valve to produce the sameresult.

The point at which the device of the present invention will causeopening of the dry-pipe valve may readily be altered without changingthe rate of flow of air through the restricted orifice, and that pointis visibly indicated by a scale exteriorly of the device. Suchadjustment is effected by varying the compression of a springcounterbalancing the air pressure in the sprinkler piping network.

Brief Description of the Drawings FIG. 1 is a view partially in sectionof an embodiment of the present invention designed for electricalcontrol of the drypipe valve of an automatic sprinkler system,illustrating diagrammatically the connection of the device to such asystem;

FIG. 2 is a detail sectional view taken on the line 2-2 of FIG. 1,showing the construction of the device supplying the restricted orifice;

FIG. 3 is a circuit diagram showing the electrical connections betweenthe device of the present invention and a solenoid valve for controllingthe dry-pipe valve;

FIG. 4 is an illustration, partly in section, of an embodiment of thepresent invention designed for fluid pressure operation, illustratingdiagrammatically the connection between such a device and a dry-pipeautomatic sprinkler system; and

FIG. 5 is a detail sectional view taken on the line 55 of FIG. 4,showing a detail of the structure of the device of FIG. 4.

.Description of the Preferred Embodiments Referring now to theaccompanying drawings and particularly to FIGS. 1 and 4 thereof, thereis shown diagrammatically a conventional dry-pipe valve M) which, forexample, is preferably of the construction illustrated in the U.S. Pat.No. 2,667,934, of Rowley although certain of the other types of drypipevalves illustrated in the Fire Protection Handbook referred to above maybe substituted therefor. The valve has its inlet side connected by apipe 12 to a water supply main I4 through a manually operable valve 16and its outlet side connected by a pipe 18 to the piping network of aconventional automatic sprinkling system 20 which, when the valve 10 isclosed, conventionally is filled with air under higher than atmosphericpressure.

The valve 10, as shown in the Rowley U.S. Pat. No. 2,667,934 referred toabove, comprises a clapper structure within which is a chamberdesignated by the reference numeral 53 in said patent, which is known atthe split seat of the dry-pipe valve and which is normally incommunication with the atmosphere through a pipe 22 and a drain clappervalve 24 corresponding to the drain clapper valve designated 93 in saidpatent; this arrangement being such that when fluid under pressure isadmitted to the pipe 22, it will effect automatic closure of the drainclapper valve 24 and cause fluid to pass under pressure into thedry-pipe valves split seat" which is the clapper valve chamberdesignated 53 in said patent, thus causing quick opening of the dry-pipevalve 10.

A pipe 25 connects the pipe 22 with a water motor operating an alarm forsignalling the opening of the dry-pipe valve 10 and a pipe 26 connectsthe pipe 25 with the inlet pipe 12 through a manually operable valve 28which may be opened at any time to test the operability of the alarm.

The elements thus far described in detail are conventional elements ofdry-pipe automatic sprinkler systems and form no part of the presentinvention.

The present invention provides, for incorporation into such a system, adevice which is responsive to a slight but rapid decrease of airpressure in the sprinkler piping network, such as the pressure decreaseattendant upon opening of a sprinkler head, to cause an immediateadmission of fluid into the pipe 22 and consequent rapid opening of thedry-pipe valve 110.

The form of the device of the present invention illustrated in FIGS. 1to 3, which is designed for electrical operation, comprises acylindrical body formed by an upper member 30 and a lower member 32secured together by bolts 34 passing through flanges 36 and 38 on theupper and lower cylindrical members respectively. The upper and lowermembers 30 and 32 are provided with internal cylindrical cavitiesdefining a compartment 37 which is divided into primary and secondarychambers 39 and 40 by piston means comprising a flexible diaphragm 42the edge of which is retained between the flanges 36 and 38, and apiston 44 to which the diaphragm 42 is centrally secured by a disk 46and bolt 48.

The piston means 42, 44 is movable longitudinally within the compartment37 to inversely vary the relative volumes of the chambers 39 and 40,that is, to increase the volume of the primary chamber 39 as the volumeof the secondary chamber 40 is decreased, and vice versa, by meanscomprising a piston rod 50 extending through a cylindrical opening 52 inthe upper member 30 and provided with an O-ring 54 which maintains anhermetic seal between the piston rod 50 and the member 30. A cylindricalspring housing 56 is secured to the upper member 30 by bolts 58, andsecured to the upper end of the piston rod 50 is a spring seat 60 guidedfor longitudinal movement within the housing 56 by a pin 62 extendingfrom the seat 60 into a slot 64 in the housing 56. A spring 66 iscompressed between the spring seat 60 and an upper spring seat 68 which,likewise is guided for longitudinal movement within the housing 56 by apin 70 extending from the upper spring seat 68 into the slot 64.

Means are provided for adjusting the compression of the spring 66 bymoving the upper spring seat 68 between the position in which it isshown in full lines and the position in which it is shown in dottedlines. This means comprises a threaded rod 72 the threads of which matewith internal threads in a central aperture 73 in the upper spring seat68 and the opposite end of which is rotatably mounted in an end closure74 secured to an end of the housing 56 by pins 76. The outside end ofthe threaded rod 72 is provided with a noncircular recess 78 into whicha mating tool may be inserted to rotate the rod 72 in one direction orthe other to alter the compression of the spring 66, and a protectivecap 80 is frictionally fitted over the end of the housing 56.

The lower chamber 40 is provided with an opening 82 which is threadedfor connection to a pipe 34 extending from the pipe 18 connected to thepiping network of the automatic sprinkler system, and a gauge 86preferably is connected to the pipe 84 for indicating the ambientpressure in the piping network and the chamber 40 which, as previouslymentioned, is conventionally maintained above atmospheric pressure. Thecompression adjustment of the spring 66 is adjusted so that itapproximately balances this pressure and thus maintains the piston means42, 44 at a position intermediate between its extreme positions withinthe compartment 37.

The chamber 39 normally is maintained at atmospheric pressure; arestricted orifice between it and the atmosphere being provided torestore the pressure therein to atmospheric pressure in the event thatrelatively slow changes in the air pressure in the network of sprinklerpiping, such as, for instance, pressure changes arising from slowlyrising or falling temperatures, cause movement of the piston means 42,44 in either direction. Such a restricted orifice is provided by acompensating vent fitting 90 threaded upon a sleeve 92 which in turn isthreaded into the enlarged upper end of a passage 94 communicating withthe chamber 39. This compensating vent fitting, as shown in detail inFIG. 2, may be, for example, a conventional component such as ismanufactured by Automatic Sprinkler Corporation of America for use inthermopneumatic systems, and in this form comprises essentially a ho]-low body member 94 within which a small mass of kapok 96 may becompressed between disks 97 and 98 by adjustment of a threaded sleeve99. Such vents are calibrated in the factory by compressing the kapok inthe vent body by screwing down the threaded sleeve 99; the rating beingstamped on the vent at the time of calibration and not usually alteredthereafter. The interior of the compensating vent fitting communicatesat one end with the opening 94 into chamber 39 and at the other end,through an aperture 100, with the atmosphere.

Means are provided for actuating an electrical switch whenever thepressure in the chamber 39 falls below atmospheric pressure by apredetermined amount in response to a drop in the pressure in chamber 40more rapid than can be offset by the induction of air from theatmosphere through the restricted orifice means comprising thecompensating vent fitting 90; This means comprises a threaded openingI02 through the wall of the member 30 into the chamber 39 into whichopening is threaded one end of a pipe fitting 104 communicating with abellows assembly 106 contractable in response to a drop in pressure inthe chamber 39 to cause closure of an electrical switch 108 ofconventional construction.

Means are provided for automatically admitting fluid pressure to thepipe 22 to cause opening of the dry-pipe valve immediately upon theclosing of the switch 100. As shown in FIG. 3, closure of switch 108completes the circuit from a source of electrical power 110 to asolenoid 112 which, when thus energized, opens a valve 114. The valve114 is disposed in a pipe 116 communicating with a source of fluidpressure such as, preferably, the water pressure supplied through thepipe 12 to the inlet side of the dry-pipe valve 10, although the airpressure in the sprinkler piping network of the automatic sprinklersystem may be utilized as such a source of fluid pressure or an entirelyindependent source of fluid pressure could be employed.

In the operation of the device of the present invention, slow changes inthe air pressure in the sprinkler piping network of the automaticsprinkler system are offset by the induction or expulsion of air fromthe chamber 39 through the compensating vent fitting 90 withouteffecting closure of the switch 108. However, in the event of a rapiddrop of air pressure in the sprinkler piping network, such as thepressure drop produced by the opening of a thermally responsive valve ofa sprinkler head, the pressure in the chamber 40 drops rapidly and thepiston means 42, 44 moves downwardly, producing a vacuum in the chamber39 too rapidly to permit it to be offset by the induction of air throughthe compensating vent 90. The production of a vacuum in the chamber 39in this manner contracts the bellows assembly 106 causing a closure ofthe electrical switch 1023, energization of the solenoid 112 and openingof the valve 114, admitting fluid pressure through the pipe 116 to apipe 22. The drain clapper valve 24 closes automatically,'as describedin Rowley, U.S. Pat. No. 2,667,934, and the fluid pressure therebycreated in the pipe 22 enters the chamber designated 53 in said patent,causing immediate opening of the dry-pipe valve 10.

The form of the device of the present invention illustrated in FIGS. 4and 5, which is designed for exclusively fluid pressure operationwithout electrical elements, comprises a cylindrical body formed by anupper member 130 and a lower member 132 secured together by bolts 134passing through flanges 136 and 138 on the upper and lower cylindricalmembers respectively. The upper and lower members 130 and 132 areprovided with internal cylindrical cavities defining a compartment 137which is divided into primary and secondary chambers 139 and 140 bypiston means comprising a flexible diaphragm 142 the edge of which isretained between the flanges 136 and 138, and a piston 144.

The piston means 142, 144 is movable longitudinally within thecompartment 137 to inversely vary the relative volumes of the chambers139 and 140; that is, to increase the volume of the primary chamber 139as the volume of the secondary chamber 140 is decreased, and vice versa,by means comprising a piston rod 150 extending through a cylindricalopening 152 in the upper member 130 and provided with an O-ring 154which maintains an hermetic seal between the piston rod 150 and themember 130. A cylindrical spring housing 156 is secured to the uppermember 130 by screws 158, and in engagement with the upper end of thepiston rod 150 is a spring seat 160 guided for longitudinal movementwithin the housing 156 by a pin 162 extending from the seat 160 into aslot 164 in the housing 156. A spring 166 is compressed between thespring seat 160 and an upper spring seat 168 which, likewise, is guidedfor longitudinal movement within the housing 156 by a pin 170 extendingfrom the upper spring seat 168 into the slot 164.

Means are provided for adjusting the compression of the spring 166 bymoving the upper spring seat 168 between the position in which it isshown in full lines and position in which it is shown in dotted lines.This means comprises a threaded rod 172 the threads of which mate withinternal threads in a central aperture 173 in the upper spring seat andthe opposite end of which is devoid of threads and is rotatably mountedin an end closure 174 secured to an end of the housing 156 by pins 176.The outside end of the threaded rod 172 is provided with a noncircularrecess into which a mating tool may be inserted to rotate the rod 1.72in one direction or the other to alter the compression of the spring166. A protective cap is frictionally titted over the end of the housing156.

The secondary chamber 140 is provided with an opening 182 which isthreaded for connection to a pipe 104 extending from the pipe 18connected to the piping network of the automatic sprinkler system, and agauge 196 preferably is connected to the pipe 184 for indicating theambient pressure in the piping network and the secondary chamber 140which, as previously mentioned, is conventionally maintained aboveatmospheric pressure. The compression adjustment of the spring 166 isadjusted so that it approximately balances this pressure and thusmaintains the piston means 142, 144 at a position intermediate betweenits extreme positions within the compartment 137.

The primary chamber 139 is normally maintained at atmospheric pressurecommunicating with the atmosphere through a restricted orifice, so thatthe pressure therein is restored to atmospheric pressure in the eventthat relatively slow changes in the air pressure in the network ofsprinkler piping, such as, for instance, pressure changes arising fromslowly rising or falling temperatures, cause movement of the pistonmeans 142, 144 in either direction.

In the embodiment of the invention shown in FIG. 4, such a restrictedorifice is provided by a compensating vent fitting 90 shown in detail inFIG. 2 and described in connection with the embodiment illustrated inFIGS. 1 to 3, this fitting, in the embodiment illustrated in FIG. 4,being threaded onto an externally threaded sleeve 191 which is in turnthreaded into an opening 193 in a member 195 defining a cavity 197communicating with the primary chamber 139 via a tube 199 the ends ofwhich are threaded into openings in "the primary chamber 139 and thewall of the cavity 197, respectively.

Means are provided for actuating a valve to permit fluid under pressureto pass from a source of fluid pressure to the split seat of thedry-pipe valve 10 whenever the pressure in the primary chamber 139 fallsbelow atmospheric pressure by a predetermined amount in response to adrop in the pressure in the secondary chamber 140 more rapid than can beoffset by the induction of air from the atmosphere through therestricted orifice means comprising the compensating vent fitting 90.This means comprises essentially a pilot valve operable in response tosuch a drop in pressure in the chamber 139 and cavity 197 which, uponsuch operation, causes opening of a main valve admitting fluid underpressure to the split seat" of the dry-pipe valve 10, i.e., the chamberdesignated by the reference numeral 53 in Rowley U.S. Pat. No. 2,667,934previously referred to.

The pilot valve comprises a valve stem 200 slidably mounted in anopening 202 in a member 204 threaded into an opening 206 in one end ofthe member 132 and sealed thereto by a gasket, as shown; the valve stem200 being sealed within the opening 202 by an O-ring as shown. At oneend of the valve stem 200 is provided with a valve head 200 which, inthe closed position of the pilot valve, engages a seat 210 retainedwithin the opening 206 in the member 132. At its opposite end the valvestem 200 is secured to a disk 212 which is adhesively secured to adiaphragm 214 the edge of which is retained between members 195 and 204by bolts 216 securing said members together. The opposite side of thediaphragm 214 is engaged by disk 216 which is urged by a spring 218compressed between the disk 216 and a wall ofthe member 195, in adirection to maintain the valve 200 in contact with its seat 210. Themember 204 defines a cavity 220 which is in communication with theatmosphere through an opening 222, so that upon a drop in pressure inthe primary chamber 139 and cavity 197 more rapid than can be offset bythe induction of air from the atmosphere through the compensating ventfitting 90, the diaphragm 214 will move downwardly, as shown in FIG. 4,against the force of the spring 218, carrying the disk 212 adhesivelysecured thereto with it and removing the valve head 208 from its seat210.

The main valve comprises a piston 224 slidably mounted in a valvechamber 226 in the member 132 and sealed to the walls thereof by anO-ring, as shown. Piston 224 is provided with a valve head 228 normallyretained against a seat 230 by a spring 232 .compressed between one endof a recess in the piston 224 and a plate 234 bolted and gasketed to theoutside wall of the member 132; the piston 224, when so positioned,dividing the valve chamber 226 into two portions.

Fluid under pressure is constantly supplied to one portion of the cavity226 from a source of fluid pressure which may be the air under pressurein the network of sprinkler piping of the automatic sprinkler system;the water under pressure in the main supply line 12; or an independentsource of fluid pressure, through pipe 236 and port 238 (see also FIG.in a wall of the cavity 226, also filling the other portion of cavity226 by virtue of a constricted port 240 in the piston 224. The fluidunder pressure also passes from the second portion of the cavity 226through a larger port 242 in the member 132 to the opening 206 in themember 132 at the inlet side of the pilot valve 208.

Because the port 240 in the piston 224 is more constricted than the port242 and the opening disclosed by the opening of the pilot valve 208 tothe outlet side of the main valve, the opening of the pilot valve 208creates a pressure differential across the piston 224, moving itleftward, as shown in FIG. 4, against the force of the spring 232, andremoving the main valve 228 from its seat 230. This permits fluid underpressure to pass from the cavity 226 into a pipe 244 threaded into anopening 246 in the member 132 communicating with the outlet side of themain valve 228 and thence to the split seat" of the dry-pipe valve 10,causing immediate opening thereof.

In the operation of this embodiment of the device of the presentinvention, slow changes in the air pressure in the sprinkler pipingnetwork of the automatic sprinkler system are offset by the induction orexpulsion of air from the chamber 139 and cavity 197 through thecompensating vent fitting 90 without displacing the pilot valve 208 fromits seat 210. However, in the event of a rapid drop of air pressure inthe sprinkler piping network, such as the pressure drop produced by theopening of a thermally responsive valve of a sprinkler head, thepressure in the chamber 139 and cavity 197 drops more rapidly than aircan be indicted through the compensating vent fitting 90, thus producinga partial vacuum in the cavity 197 and removing the pilot valve 208 fromits seat 210. The opening of the pilot valve causes, as described above,the opening of the main valve 228, permitting fluid under pressure topass from the supply pipe 236 through the main valve 228 and thencethrough the pipe 244 to the pipe 22. The drain clapper valve 24 closesautomatically, as described in the patent of Rowley U.S. Pat. No.2,667,934, and the fluid pressure thereby created in the pipe 22 entersthe split seat chamber designated 53 in said patent, causing immediateopening of the dry-pipe valve 10.

What is claimed is:

l. A quick-opening device for the dry-pipe valve of a drypipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said piston means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans adapted for connection to control the opening of dry-pipe valve ofa dry-pipe automatic sprinkler system and operable in response to adecrease in air pressure in said primary chamber valve, means responsiveto opening of said pilot valve for conby a predetermined amount belowatmospheric pressure.

2. A quick-opening device for the dry-pipe valve of a drypipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said piston means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans comprising a vacuum-responsive electrical switch adapted forconnection to control the opening of the dry-pipe valve of a drypipeautomatic sprinkler system and operable in response to a decrease in airpressure in said primary chamber by a predetermined amount belowatmospheric pressure.

3. A quick-opening device for the dry-pipe valve of a drypipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said piston means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans I adapted for connection to control the opening of the dry-pipevalve of a dry-pipe automatic sprinkler system and operable in responseto a decrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure; said control means comprising anormally closed pilot valve, a normally closed main valve adapted forconnection with a source of fluid pressure, means operable in responseto a decrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure for opening said pilot ditioning saidmain valve for opening by fluid pressure from a i source connectedthereto.

4. A quick-opening device for the dry-pipe valve of a drypipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said piston means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans adapted for connection to control the opening of the dry-pipevalve of a dry-pipe automatic sprinkler system and operable in responseto a decrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure; said control means comprising anormally closed pilot valve, a normally closed main valve comprising avalve chamber having an inlet adapted for connection to a source offluid pressure and including a valve seat, a valve piston longitudinallyslidable in said valve chamber and having an end engageable with saidseat; said piston being positioned, when engaged with said seat, todivide said valve chamber into a first portion communicating directlywith said inlet and second portion, and a restricted orifice in saidpiston connecting said first and second portions of said valve chamber;a less restricted passage connecting said second portion of said valvechamber with said pilot valve, means operable in response to a decreasein air pressure in said primary chamber by a predetermined amount belowatmospheric pressure for opening said pilot valve, whereby fluidentering said valve chamber inlet may displace said piston from saidseat.

1. A quick-opening device for the dry-pipe valve of a dry-pipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said piston means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans adapted for connection to control the opening of dry-pipe valve ofa dry-pipe automatic sprinkler system and operable in response to adecrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure.
 2. A quick-opening device for thedry-pipe valve of a dry-pipe automatic sprinkler system comprising acompartment having piston means therein dividing the same into primaryand secondary chambers; said piston means being movable to inverselyvary the relative volumes of said chambers, yieldable means forimpelling said piston means in a direction to decrease the volume of thesecondary chamber, means for connecting the secondary chamber with thepiping network of a dry-pipe automatic sprinkler system, whereby airpressure in said system may restrain movement of said piston means bysaid yieldable means, a restricted orifice connecting said primarychamber with the atmosphere, and control means comprising avacuum-responsive electrical switch adapted for connection to controlthe opening of the dry-pipe valve of a dry-pipe automatic sprinklersystem and operable in response to a decrease in air pressure in saidprimary chamber by a predetermined amount below atmospheric pressure. 3.A quick-opening device for the dry-pipe valve of a dry-pipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said pisTon means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans adapted for connection to control the opening of the dry-pipevalve of a dry-pipe automatic sprinkler system and operable in responseto a decrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure; said control means comprising anormally closed pilot valve, a normally closed main valve adapted forconnection with a source of fluid pressure, means operable in responseto a decrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure for opening said pilot valve, meansresponsive to opening of said pilot valve for conditioning said mainvalve for opening by fluid pressure from a source connected thereto. 4.A quick-opening device for the dry-pipe valve of a dry-pipe automaticsprinkler system comprising a compartment having piston means thereindividing the same into primary and secondary chambers; said piston meansbeing movable to inversely vary the relative volumes of said chambers,yieldable means for impelling said piston means in a direction todecrease the volume of the secondary chamber, means for connecting thesecondary chamber with the piping network of a dry-pipe automaticsprinkler system, whereby air pressure in said system may restrainmovement of said piston means by said yieldable means, a restrictedorifice connecting said primary chamber with the atmosphere, and controlmeans adapted for connection to control the opening of the dry-pipevalve of a dry-pipe automatic sprinkler system and operable in responseto a decrease in air pressure in said primary chamber by a predeterminedamount below atmospheric pressure; said control means comprising anormally closed pilot valve, a normally closed main valve comprising avalve chamber having an inlet adapted for connection to a source offluid pressure and including a valve seat, a valve piston longitudinallyslidable in said valve chamber and having an end engageable with saidseat; said piston being positioned, when engaged with said seat, todivide said valve chamber into a first portion communicating directlywith said inlet and second portion, and a restricted orifice in saidpiston connecting said first and second portions of said valve chamber;a less restricted passage connecting said second portion of said valvechamber with said pilot valve, means operable in response to a decreasein air pressure in said primary chamber by a predetermined amount belowatmospheric pressure for opening said pilot valve, whereby fluidentering said valve chamber inlet may displace said piston from saidseat.